12 



BULLETIN 616, U. S. DEPARTMENT OF AGRICULTURE. 



HATCHING. 



When ready to hatch, the upper end of the eggshell is broken and 

 the larva pushes through. The first impression on watching a larva 

 issue from the leaf is that the egg itself, or a minute white worm : 

 is being pushed out through the epidermis, the only movement visible 

 being a forward one. When the head and thorax 

 are free, the larva begins a series of vigorous spiral 

 movements which soon liberate the legs and antennae. 

 In some instances the antennse retain the folded 

 position until the larva has freed itself completely 

 from the tissue. When the legs are free the insect 

 pushes straight down against the leaf with the third 

 pair of feet and, alternating with abdominal move- 

 ments, brings itself into position to bend forward 

 and clasp the leaf. It then readily pulls itself out. 

 The entire operation requires from 5 to 10 minutes. 

 Hatching is not much affected by drying of the leaf or stem tissue. 

 Larvae have issued from leaves several days after the latter had be- 

 come thoroughly wilted, and from stems as long as 21 days after 

 they had been cut from the tree. 



THE LARVA. 



Fig. 4. — First -in- 

 star larva of the 

 citrus thrips. 

 Highly magnified. 

 (Original.) 



DESCRIPTION. 



First-instar larva. — Just after emergence the larva (fig. 4) is color- 

 less and translucent. The head, antenna?, mouth parts, and legs are 

 disproportionately large, giving it an ungainly ap- 

 pearance. The eyes are bright red. The average 

 length is 0.26 mm. (about 0.01 inch). The most 

 distinctive character of the first-instar larva is the 

 narrow, tapering abdomen. In a day or two the 

 body becomes suffused with yellow, which gradu- 

 ally deepens to orange in the fully developed larva. 

 As growth progresses, the head and appendages 

 lose their ungainly appearance and become more 

 symmetrical, and the abdomen grows plumper and 

 less sharply tapering. Shortly before molting to 

 the second instar the average length is 0.45 mm. 

 (about 0.017 inch). 



Second-instar larva. — The second-instar larva 

 (fig. 5) is similar in general appearance to the 

 first, except that it is more robust, more densely pigmented, and 

 the abdomen is broadly spindle-shaped, tapering gradually from 

 the middle segments in both directions. The color varies from light 

 yellow to deep orange yellow, and occasionally cream-colored in- 



Fig. 5. — Second- 

 instar larva of the 

 citrus thrips. 

 Highly magnified. 

 (Original.) 



